Buggy code:
@ SuppressWarnings ( "boxing" ) public class CollectionUtilsTest extends MockTestCase { private List < Integer > collectionA = null ; private List < Long > collectionB = null ; private Collection < Integer > collectionC = null ; private Collection < Integer > collectionD = null ; private Collection < Integer > collectionE = null ; private Collection < Number > collectionA2 = null ; private Collection < Number > collectionB2 = null ; private Collection < Number > collectionC2 = null ; private Iterable < Integer > iterableA = null ; private Iterable < Long > iterableB = null ; private Iterable < Integer > iterableC = null ; private Iterable < Number > iterableA2 = null ; private Iterable < Number > iterableB2 = null ; private Collection < Integer > emptyCollection = new ArrayList < Integer > ( 1 ) ; @ Before public void setUp ( ) { } @ Test public void getCardinalityMap ( ) { } @ Test public void cardinality ( ) { } @ Test public void cardinalityOfNull ( ) { } @ Test public void containsAll ( ) { } @ Test public void containsAny ( ) { } @ Test public void union ( ) { } @ Test public void intersection ( ) { } @ Test public void disjunction ( ) { } @ Test public void testDisjunctionAsUnionMinusIntersection ( ) { } @ Test public void testDisjunctionAsSymmetricDifference ( ) { } @ Test public void testSubtract ( ) { } @ Test public void testSubtractWithPredicate ( ) { } @ Test public void testIsSubCollectionOfSelf ( ) { } @ Test public void testIsSubCollection ( ) { } @ Test public void testIsSubCollection2 ( ) { } @ Test public void testIsEqualCollectionToSelf ( ) { } @ Test public void testIsEqualCollection ( ) { } @ Test public void testIsEqualCollectionReturnsFalse ( ) { } @ Test public void testIsEqualCollection2 ( ) { } @ Test public void testIsEqualCollectionEquator ( ) { final Collection < Integer > collB = CollectionUtils . collect ( collectionB , TRANSFORM_TO_INTEGER ) ; final Equator < Integer > e = new Equator < Integer > ( ) { public boolean equate ( final Integer o1 , final Integer o2 ) { if ( ( ( ( o1 . intValue ( ) ) % 2 ) == 0 ) ^ ( ( ( o2 . intValue ( ) ) % 2 ) == 0 ) ) { return false ; } else { return true ; } } public int hash ( final Integer o ) { return ( ( o . intValue ( ) ) % 2 ) == 0 ? Integer . valueOf ( 0 ) . hashCode ( ) : Integer . valueOf ( 1 ) . hashCode ( ) ; } } ; assertTrue ( CollectionUtils . isEqualCollection ( collectionA , collectionA , e ) ) ; assertTrue ( CollectionUtils . isEqualCollection ( collectionA , collB , e ) ) ; assertTrue ( CollectionUtils . isEqualCollection ( collB , collectionA , e ) ) ; <START_BUG> final Equator < Number > defaultEquator = new org . apache . commons . collections4 . functors . DefaultEquator < Number > ( ) ; <END_BUG> assertFalse ( CollectionUtils . isEqualCollection ( collectionA , collectionB , defaultEquator ) ) ; assertFalse ( CollectionUtils . isEqualCollection ( collectionA , collB , defaultEquator ) ) ; } @ Test ( expected = IllegalArgumentException . class ) public void testIsEqualCollectionNullEquator ( ) { } @ Test public void testIsProperSubCollection ( ) { } @ Test public void find ( ) { } @ SuppressWarnings ( { "unchecked" , "rawtypes" } ) @ Test public void forAllDoCollection ( ) { } @ SuppressWarnings ( { "unchecked" , "rawtypes" } ) @ Test public void forAllDoIterator ( ) { } @ Test ( expected = FunctorException . class ) public void forAllDoFailure ( ) { } @ Test public void forAllButLastDoCollection ( ) { } @ Test public void forAllButLastDoIterator ( ) { } @ Test public void getFromMap ( ) { } @ Test ( expected = IndexOutOfBoundsException . class ) public void getFromList ( ) throws Exception { } @ Test public void getFromIterator ( ) throws Exception { } @ Test public void getFromEnumeration ( ) throws Exception { } @ Test ( expected = IndexOutOfBoundsException . class ) public void getFromIterable ( ) throws Exception { } @ Test ( expected = IndexOutOfBoundsException . class ) public void getFromObjectArray ( ) throws Exception { } @ Test ( expected = IndexOutOfBoundsException . class ) public void getFromPrimativeArray ( ) throws Exception { } @ Test ( expected = IllegalArgumentException . class ) public void getFromObject ( ) throws Exception { } @ Test public void testSize_List ( ) { } @ Test public void testSize_Map ( ) { } @ Test public void testSize_Array ( ) { } @ Test public void testSize_PrimitiveArray ( ) { } @ Test public void testSize_Enumeration ( ) { } @ Test public void testSize_Iterator ( ) { } @ Test ( expected = IllegalArgumentException . class ) public void testSize_Other ( ) { } @ Test public void testSizeIsEmpty_Null ( ) { } @ Test public void testSizeIsEmpty_List ( ) { } @ Test public void testSizeIsEmpty_Map ( ) { } @ Test public void testSizeIsEmpty_Array ( ) { } @ Test public void testSizeIsEmpty_PrimitiveArray ( ) { } @ Test public void testSizeIsEmpty_Enumeration ( ) { } @ Test public void testSizeIsEmpty_Iterator ( ) { } @ Test public void testSizeIsEmpty_Other ( ) { } @ Test public void testIsEmptyWithEmptyCollection ( ) { } @ Test public void testIsEmptyWithNonEmptyCollection ( ) { } @ Test public void testIsEmptyWithNull ( ) { } @ Test public void testIsNotEmptyWithEmptyCollection ( ) { } @ Test public void testIsNotEmptyWithNonEmptyCollection ( ) { } @ Test public void testIsNotEmptyWithNull ( ) { }

Fix:
final Equator < Number > defaultEquator = DefaultEquator . defaultEquator ( ) ;